The present invention relates to an apparatus for detecting output state of internal-combustion engine.
Cars equipped with an engine and a motor-generator (functioning as a motor or as a generator), e.g., so-called hybrid cars are recently available for use. In such hybrid cars, in order to run the engine in the efficient range of the engine revolutions, the engine and the motor-generator are connected via a planetary gear and the motor-generator is controlled to maintain the engine speed (revolutions) at the efficient revolutions.
The inventors found that in the cars having the engine and the motor-generator it was difficult to detect an output state of the internal-combustion engine, based on the angular velocity of rotation thereof, because the motor-generator was designed to control the angular velocity of rotation of the output shaft of the engine to a substantially constant level.
Accordingly, an object of the present invention is to provide output state detecting apparatus that can detect an output state of an internal-combustion engine, in vehicles and others having the internal-combustion engine and the motor.
For example, there is the technique disclosed in Japanese Patent Application Laid-Open No. H02-49955, as a device for detecting misfiring (the output state of the internal-combustion engine) in cylinders of the internal-combustion engine due to trouble in the fuel valve and/or the ignition system. This technique is to detect the angular velocity of rotation of the output shaft of the engine and determine an abnormal cylinder suffering misfiring, based on anomaly of angular velocity. However, since the engine speed is controlled by the motor-generator in the cars having the engine and the motor-generator as described above, it is hard to detect the combustion state (output state), based on the engine speed, as in this technique.
As another technique, the fuel quality is detected in order to run the internal-combustion engine stably and reduce pollutant components in exhaust gas emitted. Since the output of the internal-combustion engine can vary depending upon change of the fuel quality, the fuel quality can be regarded as one of output states of the internal-combustion engine. For example, the device described in Japanese Patent Application Laid-Open No. H09-256898 is known as a fuel quality detecting device. The fuel quality detecting device described in No. H09-256898 is designed to determine the fuel quality, based on change of the engine speed during driving auxiliary accessory devices.
When the fuel quality is heavy and when the fuel attaches, for example, to the internal wall of the intake pipe (intake port) upon a cold start, the attaching fuel becomes resistant to evaporation. Unless the fuel quality is detected and unless fuel injection quantity is corrected based on the result of the detection, the air-fuel ratio will tend to become lean. This will lead to instable output and running states of the internal-combustion engine and/or to increase in the amount of pollutant substances in the exhaust gas.
However, since the engine speed is controlled by the motor-generator in the cars having the engine and the motor-generator (for driving of road wheels and for power generation), variation of engine speed is very small and it is considerably difficult to determine the fuel quality from the variation of engine speed.
An output state detecting apparatus according to the present invention comprises an internal-combustion engine, a generator driven by the internal-combustion engine to generate electric power, torque detecting means for detecting a reaction torque of the generator, and output state detecting means for detecting an output state of the internal-combustion engine, wherein the output state detecting means detects the output state of the internal-combustion engine, based on the reaction torque of the motor detected by the torque detecting means.
Since the motor generates electric power while receiving the output of the internal-combustion engine, the reaction torque of the motor reflects the output of the internal-combustion engine. Therefore, the present invention permits the detection of the output state of the internal-combustion engine based on the reaction torque of the motor.